A cogeneration system is a system which supplies electric power generated in power generation to a customer to cover a power load of the customer, and recovers and stores exhaust heat resulting from the power generation to cover a hot water load of the customer. As such a cogeneration system, there is known a cogeneration system in which a fuel cell and a hot water supply device are configured to operate using the same fuel (e.g., see Patent Literature 1). The cogeneration system disclosed in Patent Literature 1 includes a fuel cell, a heat exchanger for recovering heat generated by an operation of the fuel cell, a hot water storage tank for storing water heated after it has circulated through the heat exchanger, and a hot water supply device for heating the water flowing out of the hot water storage tank up to a predetermined temperature, and is configured such that the fuel cell and the hot water supply device operate using the same fuel.
There is also known a fuel cell power generation apparatus intended to improve an exhaust performance of the fuel cell power generation apparatus placed inside of a building (e.g., see Patent Literature 2). The power generation apparatus disclosed in Patent Literature 2 is a fuel cell power generation apparatus installed and used inside of a building having an intake port. The power generation apparatus includes an air introduction port through which air is guided from inside of the building to inside of the fuel cell power generation apparatus, an air exhaust pipe through which the air inside of the fuel cell power generation apparatus is exhausted to outside of the building, and a ventilation means. The ventilation means guides the air outside of the building to inside of the building via the intake port, then introduces the air to inside of the fuel cell power generation apparatus through the air introduction port, and then exhausts the air to outside of the building through the air exhaust pipe.
There is also known a power generation apparatus including a duct extending vertically for improving an exhaust performance of an exhaust gas generated in a fuel cell placed inside of a building (e.g., see Patent Literature 3). In the power generation apparatus disclosed in Patent Literature 3, the duct extending vertically inside of the building and having an upper end portion located outside has a double-wall-pipe structure, and a ventilation pipe and an exhaust pipe are coupled to the duct so that the exhaust gas or air flows individually in an inner side or an outer side of the duct.